Imaging Case of the Week 14

The wrist x-ray shows Bennett’s fracture which is most common type of fracture of the base of thumb.

Bennett’s fracture is an intraarticular fracture of base of the thumb metacarpal bone. A small triangular proximal fragment remains attached to the trapezium and the metacarpal shaft is displaced proximally and radially.

The metacarpal shaft displacement is caused by the pull of APL(abductor pollicis longus and adductor pollicis) and this often causes problems with closed reduction.

Clinically, there will be swelling and bruising over the base of thumb. Pinch grasp and opposition will be affected.

Patient needs referral to orthopaedician or hand specialist depending on departmental policy. Closed reduction can be tried with traction to the thumb and abduction,extension and pronation of the thumb followed by thumb spica. But reduction is often difficult to maintain and often these patients end up requiring closed reduction followed by K wire pinning or open reduction and internal fixation.

There are two other fractures of base of thumb. Extraarticular fracture and Rolando’s fracture. Rolando’s fracture is comminuted (T or Y shaped) intraarticular fracture of thumb base, can be difficult one to treat.